1. Field of the Invention
This invention relates to a method of accelerating the curing of a vinyl ester resin. More specifically, the invention relates to the room temperature accelerating of vinyl ester adhesives.
2. Description of the Prior Art
It is generally known that the rate of reaction for radical polymerization can be enhanced by application of heat or ultra-violet light to activate (decompose into radicals) the free radical initiator or, in some instances, by the presence of a promoter/accelerator (e.g., polyvalent metal naphthenates or octoates, tertiary amines or mercaptans). Thus, it is known that in the case of the formation of cross-linked structure by the addition of a free radical initiator (e.g., benzoyl peroxide, or methyl ethyl ketone peroxide) to a polyester resin (which for purposes of this invention refers to a polymer having unsaturation distributed in the backbone) in a reaction monomer (e.g., styrene) admixture, the cross-linking reaction (curing) can be sped up by the addition of an accelerator (e.g., cobalt naphthenate or dimethylamine) particularly in room temperature curing applications. More specifically, the cross-linking of an unsaturated polyester resin based on bisphenol A and fumaric acid with styrene monomer and methyl ethyl ketone peroxide (MEKP) with a cobalt soap promoter has been reported in chemical literature as being copromoted by dimethylaniline (DMA), ethyl acetoacetate (EAA) and methyl acetoacetate (MAA). However, in the case of accelerating, at room temperature, a similar admixture containing a vinyl ester resin (which for purposes of this invention refers to a polymer having only terminal unsaturation) only the toxic N,N, dimethylaniline is known as a copromoter/accelerator.